US4493990A - Apparatus for automatically adjusting a deflection unit - Google Patents

Apparatus for automatically adjusting a deflection unit Download PDF

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Publication number
US4493990A
US4493990A US06/425,909 US42590982A US4493990A US 4493990 A US4493990 A US 4493990A US 42590982 A US42590982 A US 42590982A US 4493990 A US4493990 A US 4493990A
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Prior art keywords
input
output
adjustment
deflection unit
memory
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Expired - Fee Related
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US06/425,909
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English (en)
Inventor
Gunther Koszytorz
Herbert Lucke
Gerhard Schlosser
Joachim Vath
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Siemens AG
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Siemens AG
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Assigned to SIEMENS AKTIENGESELLSCHAFT, reassignment SIEMENS AKTIENGESELLSCHAFT, ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: KOSZYTORZ, GUNTHER, LUCKE, HERBERT, SCHLOSSER, GERHARD, VATH, JOACHIM
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/04—Automatically aligning, aiming or focusing the laser beam, e.g. using the back-scattered light
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/04—Automatically aligning, aiming or focusing the laser beam, e.g. using the back-scattered light
    • B23K26/042—Automatically aligning the laser beam
    • B23K26/043—Automatically aligning the laser beam along the beam path, i.e. alignment of laser beam axis relative to laser beam apparatus
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/08—Devices involving relative movement between laser beam and workpiece

Definitions

  • This invention relates generally to arrangements for controlling and adjusting deflection units, and more particularly, to a system which automatically adjusts the characteristics of the deflection unit with respect to its coordinate origin and the slope of the deflection function.
  • deflection units are required, for example, to adjust deflection mirrors for the laser beams in laser recording equipments.
  • a position signal is sensed by an actual-value measuring circuit and compared against a reference value.
  • a controller which controls the deflection unit brings the position signal into agreement with the reference value.
  • the actual-value measuring circuits which are commonly used are of a type which operates with a capacitive sensor which is subject to thermal drift which produces a deviation between the preset reference value and the actual position of the deflection mirror. Such a deviation produces displacements and scale changes in the recording field.
  • the temperature drift produces not only a shift in the origin of the characteristic, but also a change in its slope.
  • an object of the invention to provide an arrangement for adjusting the linear characteristic of deflection unit so that automatic adjustment is achieved.
  • this invention provides an arrangement for automatically adjusting the characteristic of a deflection unit with respect to origin and slope, the arrangement having a multiplier having a first input for receiving a reference value for the deflection unit, and a second input which is connected to the output of a first memory.
  • the multiplier is coupled at its output to a first input of an adder; the adder being connected at its second input to the output of a second memory.
  • a position measuring device which produces a position measuring signal for the deflection unit is connected to a first input of a comparator.
  • the comparator receives at a second input thereof a zero value as a first adjustment reference value if a "zero-adjustment command" has been issued.
  • a second adjustment reference value is present at the second input of the comparator if a "slope-adjustment command" has been issued.
  • the comparator is provided with a first output for producing a signal if the position measuring signal at the first input thereof is larger than the value at the second input.
  • a signal is produced at a second output of the comparator if the position measuring signal at the first input is smaller than the valve at the second input. If a "zero-adjustment command" has been issued, the first adjustment reference value "zero" is provided as the reference value for the deflection unit.
  • the content of the second memory is incremented if a signal is present at the first output of the comparator.
  • the second memory is decremented if a signal is present at the second output of the comparator. Such incrementing or decrementing is continued unitl none of the outputs of the comparator bears a signal. If a "slope-adjustment command" has been issued, the second adjustment reference value is provided as the reference value for the deflection unit, and the content of the first memory is incremented if a signal is present at the first output of the comparator. If a signal is present at the second output of the comparator, the content of the first memory is decremented. The incrementing or decrementing processes are continued until none of the outputs of the comparator bears a signal.
  • the automatic adjustment of the zero point, as well as the slope of the characteristic of the deflection unit is achieved.
  • Such a compensating adjustment is achieved in a relatively short time, thereby permitting it to be performed periodically.
  • Such automatic adjustment is possible in any operating condition.
  • the first and second memories are loaded, prior to the adjustment, with values which are smaller than the values expected after the adjustment is completed. Thus, only incrementation of the contents of the first and second memories takes place. Since, under this mode of operation, the contents of the memories are changed in only one direction, the comparator need only determine whether the position measuring signal is still smaller than the predetermined value.
  • the desired adjustment values are stored in a third memory which receives at its address inputs the zero-adjusting command and the slope-adjusting command.
  • the outputs of the third memory are connected to the first input of the multiplier and to the second input of the comparator. In this manner, fixed adjusting values can be preprogrammed.
  • a double-throw switch is electrically interposed between the third memory and the first input of the multiplier.
  • the doube-throw switch receives at a first input thereof a signal corresponding to the desired value of the deflection unit.
  • the second input of the double-throw switch is connected to the output of the third memory, and switches, in the event of a "slope-adjusting command," or a "zero-adjusting command,” from the first to the second input. With this switch, the reference value which is entered into the deflection unit is automatically converted to the adjustment reference value during the adjustment process.
  • the first and second memories may be easily embodied as first and second counters, respectively.
  • a clock generator is provided which operates on the increment and decrement inputs of the first and second counter/memories by producing counting pulses.
  • the clock generator is connected to the respective first inputs of four AND gates.
  • the "zero-adjustment command" is present at the respective second inputs of the first and second AND gates, and the “slope-adjustment command” is present at the respective input of the third and fourth AND gates.
  • the first output of the comparator is connected to the respective third input of the second and fourth AND gates, and the second output of the comparator is connected to the respective third inputs of the first and third AND gates.
  • the output of the first AND gate is connected to the increment input of the second memory/counter, the output of the second AND gate is connected to the decrement input of the second memory/counter, the output of the third AND gate is connected to the increment input of the first memory/counter, and the output of the fourth AND gate is connected to the decrement input of the first memory/counter.
  • a drive of the counters with increment and decrement pulses is required to perform the adjustment process.
  • the first, second, and third memories may also be buffer memories which are appropriately loaded from the data bus of a microprocessor or a computer.
  • the adjustment arrangement can be addressed in conjunction with a microprocessor or computer in a particularly simple manner.
  • the position measuring device may contain a plate which is connected to the shaft of the deflection unit.
  • the plate is arranged in the light path between a light transmitter and a light receiver which delivers the position measuring signal.
  • the plate is provided with a first slit aperture which is in the light path at the zero position of the deflection unit.
  • a second slit aperture in the plate lies in the light path if the position of the deflection unit agrees with the second reference value.
  • the light receiver may advantageously be configured as a differential photodiode.
  • the output signal of this differential photodiode is zero at both adjustment points, so that only a comparison with the "zero" signal is necessary for adjustment.
  • the comparator is thereby simplified to a limit indicator.
  • FIG. 1 is a block and line representation of a known control arrangement for a deflection unit which is in common use in laser recording equipment;
  • FIG. 2 is a graph showing the effects of thermal drift on the actual-value measuring circuit
  • FIG. 3 is a block and line representation of an automatic circuit arrangement constructed in accordance with the principles of the invention for adjusting the characteristic of a deflection unit;
  • FIG. 4 is a block and line representation of a computerized embodiment of the invention.
  • FIG. 5 is a schematic representation of a position measuring device.
  • FIG. 1 is a block and line representation of a prior art control arrangement for a deflection unit A of the type which is commonly used, for example, in laser recording equipments.
  • deflection unit A moves a mirror Sp, the actual position of which is measured with an actual-value measuring circuit M.
  • Measuring circuit M may be of the type which contains a capacitive position pickup. The measured value of the actual position is compared against a position reference value L soll in a comparator V. The control difference is conducted to a controller R which drives deflection unit A.
  • FIG. 2 is a graph of various deflection unit characteristics in accordance with which the deflection unit may operate.
  • characteristic A shown in FIG. 2 is the ideal operating characteristic for the deflection unit.
  • a writing beam deflection, along the small y axis, of 0.02 mm corresponds to one step of the reference value, L soll , along the x axis.
  • L soll the reference value
  • a beam deflection totaling ⁇ 40 mm is obtained.
  • the actual-value measuring circuit M is subject to thermal drift so that the measured value for the actual position does not agree with the actual position of the deflection mirror. This results in a parallel shift, as well as in a change of the slope of characteristic A, so as to cause the deflection unit to operate in accordance with characteristic B which is also shown in FIG. 2.
  • characteristic B a reference value signal of +2,000 or -2,000, respectively, results in a beam deflection of approximately +32 or -42 mm, respectively.
  • the position reference value L soll must be changed correspondingly. In this manner, the characteristic of the deflection unit can be matched to its desired characteristic.
  • characteristic B is first shifted so that it runs through the origin of the coordinate system, such as characteristic B', shown in dashed line.
  • Such a shift in characteristic B can be achieved by adding a predetermined amount to reference value L soll .
  • characteristic B' must also be rotated, and this can be achieved by multiplication by a constant factor.
  • the described adjustment is advantageously performed at two adjustment points, the first adjustment point being at zero for shifting the characteristic in a parallel manner, and a second adjustment point which is different from zero, for rotating the characteristic.
  • FIG. 3 shows a block and schematic representation of a circuit arrangement constructed in accordance with the invention for performing automatically the adjustments to the characteristic of the deflection unit.
  • the position reference value L soll which is present at input E1 is conducted via a double-throw switch 6 to the first input of a multiplier 1.
  • the second input of multiplier 1 is connected to the output of a memory 3.
  • the multiplication process which is effected by this arrangement produces the described rotation of the characteristic.
  • the output of multiplier 1 is connected to a first input of an adder 2, the second input of which is connected to a second memory 4. With adder 2, the described parallel shift of the characteristic is achieved, so that the corrected reference value L soll ' is present at the output of the adder.
  • the memories 3 and 4 are loaded with the values required to perform the adjustment. As described, a dual-adjusting operation is required to perform the zero and slope adjustments.
  • the zero adjustment command is provided, the command being conducted to an address input of a third memory 5, to the respective second inputs of two AND gates 8 and 9, and to an input of an OR gate 14.
  • OR gate 14 produces at its output a signal which addresses the double-throw switch 6 and thereby switches the first input of multiplier 1 from input E1 to the output of memory 5.
  • the corresponding adjustment reference value was selected by the "zero-adjustment command," which in this case has the value zero.
  • Memory 4 must then be set so that the writing beam actually occupies the zero position.
  • a separate position measuring device 13 is provided which must have no temperature error. Since this position measuring device 13 must scan the position of the light beam at only two points, illustratively the zero point and at another adjustment point, this process is easily realized, as will be described hereinbelow.
  • the output signal of position measuring device 13 is conducted to comparator 12, the reference input of which is connected to the output of memory 5. Since, in the event of a "zero-adjustment command," a zero signal is present at the output of memory 5, the position measurement signal of position measuring device 13 is thus compared against zero.
  • Comparator 12 is provided with two inputs, 12a and 12b. A "1" signal is present at output 12a if the position measuring signal is larger than the reference value, and a "1" signal is present at output 12b if the position measuring signal is smaller than the reference signal.
  • Output 12a of comparator 12 is connected to the third input of AND gate 9 and the output 12b is connected to the third input of the AND gate 8.
  • the output of a clock generator 7 is connected to the respective first inputs of the two AND gates 8 and 9.
  • the output of AND gate 8 is connected to the increment input IV of memory/counter 4, and the output of AND gate 9 is connected to decrement input IR of counter 4.
  • the clock pulses of clock generator 7 are connected to the increment input of memory/counter 4 during a "zero-adjustment command," if the position measuring signal is smaller than zero, and to the decrement input if the position measuring signal is larger than zero.
  • the memory/counter is brought to a value such that if a reference value of zero is provided, the writing beam actually occupies the zero position. As explained, this is accomplished by adding the counter reading of memory/counter 4 to the desired (reference) value in adder 2. Thus, a parallel shift of the characteristic to be adjusted is achieved. This completes the zero adjustment.
  • position measuring device 13 supplies the second adjustment reference value as the output variable if the writing beam is adjusted to the second adjustment point.
  • Position measuring device 13 can also supply the output value "zero" at the second adjustment point, as shown, for example, in the illustrative embodiment which will be described below. In this case, the value is, of course, entered as the reference value.
  • the position measuring device can also supply any desired position measuring signal at the second adjustment point if the former is stored in the memory and is optionally conducted to the reference input of comparator 12.
  • the comparator then checks, at the second adjustment point, whether the delivered position measuring signal is larger or smaller than the comparison value.
  • output 12b of comparator 12 is connected to the third input of an AND gate 10, and output 12a is connected to the third input of an AND gate 11.
  • the output of AND gate 10 is connected to the increment input IV of memory/counter 3, and the output of AND gate 11 is connected to the decrement input IR of memory/counter 3.
  • the output of clock generator 7 is connected to the first inputs of AND gates 8 and 9.
  • counter 3 is therefore advanced by the clock pulses from clock generator 7 until the position of the writing beam agrees with the given second adjustment reference value. This is achieved, as explained, by feeding the output signal of counter 3 to the second input of multiplier 1. Such a multiplication achieves a rotation of the characteristic B' until it conforms to characteristic A. This completes the slope adjustment.
  • double-throw switch 6 is switched back again, so that the position reference value L soll is again entered into the deflection unit.
  • the readings in memory/counters 3 and 4 are preserved until the next adjustment process, so that there is agreement between the characteristic of the deflection unit and its desired characteristic, at least for a certain operating range.
  • the adjustment process can take place, for example, at fixed intervals, illustratively after a given number of lettering operations, or upon request. During this process, the period of the clock pulses is selected so that a possible transient of the deflection unit always has decayed between subsequent clock pulses.
  • comparator 12 must be monitored with respect to whether the position measuring signal is larger or smaller than the adjustment reference value. Along with such monitoring, two output signals of comparator 12 must be processed.
  • counters 3 and 4 can also be set to values which are below the values expected after the adjustment is made. This can be done, for example, by a setting signal at input E2, which is connected to the respective setting inputs S of counters 3 and 4 by the dashed lines shown in FIG. 3.
  • the predetermined values to which memory/counters 3 and 4 are to be set are present at their respective presetting inputs Z1. In this case, only the smaller signal or output 12b of comparator 12 is evaluated. The readings of memory/counters 3 and 4 are incremented until the signal at output 12b has disappeared. Since the decrementing of counters 3 and 4 is eliminated, AND gates 9 and 11 can also be omitted.
  • FIG. 4 shows a block and line representation of an illustrative computerized arrangement for performing the automatic adjustment.
  • memories 3, 4, and 5 are realized as buffer memories which are loaded by a microprocessor or computer 15 via a data bus 16.
  • Buffer memories 3-5 each contain a digital-to-analog converter which converts the digital signals of the microprocessor into analog values for further processing.
  • the digital-to-analog converter of buffer memory 5 is designed as a multiplying converter, the multiplying input of which is connected to the output of buffer memory 3.
  • Outputs 12a and 12b of comparator 12 are similarly coupled via a buffer memory 18 to data bus 16. In the embodiment of FIG. 4, it is assumed that the position measurement signal of position measuring device 13 goes to zero for every adjustment reference value.
  • Comparator 12 therefore, compares the position measurement signal always against zero, so that setting a separate comparison voltage is not necessary.
  • Comparator 12 may be designed here as a window discriminator which delivers a signal at outputs 12a and 12b, respectively, only if the input signal lies outside a bandwidth about the zero point.
  • computer 15 sets buffer memory 5 to the position reference value for the deflection unit, so that the deflection unit is adjusted accordingly.
  • the computer sets the input signal of buffer memory 5 to zero during the zero adjustment.
  • microprocessor 15 feeds to buffer memories 3 and 4 values which lie below the expected values in the adjusted state.
  • Output 12b of comparator 12 interrogates, via buffer memory 18, whether the smaller signal is present. If such is the case, the content of buffer memory 4 is increased by one. Then output 12b of comparator 12 is interrogated again as to whether the smaller signal is still present. The content of buffer memory 4 is increased until the smaller signal at output 12b of comparator 12 has disappeared. Between the interrogation processes, a transient time of deflection mirror Sp is optionally being waited for. In this manner, the zero adjustment is completed.
  • a second adjustment value which is different from zero, and lies as far as possible in the vicinity of the end deflection of mirror Sp, or agrees with the latter, is set into buffer memory 5.
  • the content of the buffer memory remains unchanged.
  • the smaller signal at output 12b of comparator 12 is again interrogated and the content of buffer memory 3 is incremented until the smaller signal has disappeared. This completes the adjustment and computer 15 can again set the position reference value for deflection unit A in normal operation.
  • FIG. 5 is a schematic representation of an illustrative embodiment of positioning measuring device 13.
  • position measuring device 13 is intended to accurately determine the position of the deflection unit A at two adjustment points, one of which is the zero points.
  • position measuring device 13 must not be subject to thermal drift.
  • Position measuring device 13 contains a light emitter 13a which may, for example, be a light-emitting diode. Opposite to light-emitting diode 13a is arranged is a light receiver 13c which may, for example, a differential photodiode. Light receiver 13c is arranged on a mounting 13b. In one embodiment, light receiver 13c contains two photodiode sections, the output voltages of which are connected to buck one another. If, therefore, a light ray illuminates the separating line between the two diodes sections, these are illuminated with the same intensity, and since the output voltages of both photodiodes sections are equal, the output voltage of the entire differential photodiode is zero.
  • the output voltage of the entire differential photodiode becomes either positive or negative, depending upon the direction of the deflection.
  • a disc 13d which is firmly coupled to a shaft of deflection unit A, is interposed in the light path between light emitter 13a and light receiver 13c.
  • Disc 13d has two slit apertures 13e and 13f which are arranged so that each slit aperture lies at one of the two adjustment points exactly between light emitter 13a and the separating line between the two photodiode sections of differential photodiode 13c. In this manner, the output signal of position measuring device 13 becomes zero as soon as the deflection unit A has reached one of the two adjustment points.
  • Light receiver 13c is advantageously arranged to be positionally adjustable by means of an adjusting screw 13g. This permits the position of one of the adjustment points, preferably the zero point, to be adjusted. Such adjustability permits compensation for manufacturing tolerances for the first slit 13e, or for the attachment of disc 13d at the shaft of deflection unit A. Compensation for the manufacturing tolerances with respect to the distance between the two slit apertures 13e and 13f, which would relate to the second adjustment point, can be performed as follows: the second adjustment point is not fixed from the start, but it is first determined at which point the position measuring device delivers the voltage zero. This point would then be selected as the second adjustment reference point. The second adjustment reference point needs to be determined only once and should remain the same, if the apertures are made by machine, at least for each production lot.

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Percussion Or Vibration Massage (AREA)
  • Cookers (AREA)
  • Electron Beam Exposure (AREA)
  • Dot-Matrix Printers And Others (AREA)
  • Laser Beam Printer (AREA)
  • Mechanical Optical Scanning Systems (AREA)
  • Control Of Position Or Direction (AREA)
  • Moving Of The Head For Recording And Reproducing By Optical Means (AREA)
  • Photometry And Measurement Of Optical Pulse Characteristics (AREA)
  • Lasers (AREA)
  • Length Measuring Devices By Optical Means (AREA)
  • Manufacturing Optical Record Carriers (AREA)
US06/425,909 1981-10-23 1982-09-28 Apparatus for automatically adjusting a deflection unit Expired - Fee Related US4493990A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3142152 1981-10-23
DE3142152A DE3142152C2 (de) 1981-10-23 1981-10-23 Vorrichtung zum automatischen Abgleich der Kennlinie einer Ablenkeinheit

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US4493990A true US4493990A (en) 1985-01-15

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US (1) US4493990A (de)
EP (1) EP0077970B1 (de)
JP (1) JPS5886610A (de)
AT (1) ATE12600T1 (de)
DE (2) DE3142152C2 (de)

Cited By (4)

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DE3517671A1 (de) * 1985-05-15 1986-11-20 Messerschmitt-Bölkow-Blohm GmbH, 8012 Ottobrunn Vorrichtung zum bildpunktweisen erfassen der oberflaechengestalt eines entfernten objektes
US4652749A (en) * 1985-03-21 1987-03-24 Robotic Vision Systems, Inc. Optical coordinate measuring system with dual path reflecting means
US5208123A (en) * 1989-05-18 1993-05-04 Pilkington P.E. Limited Hologram construction
US20090103156A1 (en) * 2007-10-17 2009-04-23 Samsung Electronics Co., Ltd. Image forming apparatus with laser scanning device and method of aligning the laser scanning device

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Publication number Priority date Publication date Assignee Title
WO1993001233A1 (en) * 1991-07-10 1993-01-21 Seiko Epson Corporation Transparent plastic material
JP2002090682A (ja) * 2000-09-19 2002-03-27 Matsushita Electric Ind Co Ltd ガルバノメータ、ガルバノメータの位置補正方法、ガルバノメータを用いたレーザ加工装置、及びガルバノメータを用いたレーザ加工方法
TWI235555B (en) 2004-03-18 2005-07-01 Mediatek Inc DAC DC offset calibration method and related apparatus

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US4264809A (en) * 1979-05-02 1981-04-28 Eastman Kodak Company Servo control loop using optical feedback
US4417330A (en) * 1981-10-15 1983-11-22 Burroughs Corporation Optical memory system providing improved focusing control

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US3814895A (en) * 1971-12-27 1974-06-04 Electroglas Inc Laser scriber control system
DE2335517C3 (de) * 1973-07-12 1980-04-30 Siemens Ag, 1000 Berlin Und 8000 Muenchen Verfahren zur Kompensation von Lageabweichungen eines Zifferblattes oder Schildes relativ zu einem Beschriftungsgerät
FR2373819A1 (fr) * 1976-12-09 1978-07-07 Burroughs Corp Installation et procede de positionnement notamment pour tetes de lecture de disque
US4125755A (en) * 1977-06-23 1978-11-14 Western Electric Co., Inc. Laser welding
US4218606A (en) * 1978-10-03 1980-08-19 Olin Corporation Apparatus for perforating webs with high intensity, coherent radiation

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US4264809A (en) * 1979-05-02 1981-04-28 Eastman Kodak Company Servo control loop using optical feedback
US4417330A (en) * 1981-10-15 1983-11-22 Burroughs Corporation Optical memory system providing improved focusing control

Non-Patent Citations (2)

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Title
Patent Abstracts of Japan, Jun. 9, 1981, vol. 5, No. 88, 56 35222. *
Patent Abstracts of Japan, Jun. 9, 1981, vol. 5, No. 88, 56-35222.

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4652749A (en) * 1985-03-21 1987-03-24 Robotic Vision Systems, Inc. Optical coordinate measuring system with dual path reflecting means
DE3517671A1 (de) * 1985-05-15 1986-11-20 Messerschmitt-Bölkow-Blohm GmbH, 8012 Ottobrunn Vorrichtung zum bildpunktweisen erfassen der oberflaechengestalt eines entfernten objektes
US5208123A (en) * 1989-05-18 1993-05-04 Pilkington P.E. Limited Hologram construction
US20090103156A1 (en) * 2007-10-17 2009-04-23 Samsung Electronics Co., Ltd. Image forming apparatus with laser scanning device and method of aligning the laser scanning device
US8027073B2 (en) * 2007-10-17 2011-09-27 Samsung Electronics Co., Ltd. Image forming apparatus with laser scanning device and method of aligning the laser scanning device

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EP0077970A1 (de) 1983-05-04
DE3142152A1 (de) 1983-05-26
EP0077970B1 (de) 1985-04-10
DE3142152C2 (de) 1984-05-24
JPS5886610A (ja) 1983-05-24
DE3263013D1 (en) 1985-05-15
ATE12600T1 (de) 1985-04-15

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